I’m not sure what’s happened to cause this, but following recent Plasma updates, on one system it can’t show the individual core or memory usage applets. That system shows them for selection, but then the panel shows a generic icon and ‘unknown applet’. There are a couple of other systems here and these do not show the problem. Before I just give up and reinstall the affected machine, I wondered if anyone had seen something similar and had been able to fix it. I tried copying over the /lib/qt6/plugins/plasma/applets/ folder from one of the unaffected systems, but it didn’t help.